KR100900569B1 - Method of forming floating gate and method of fabricating non-volatile memory device using the same - Google Patents

Abstract

The present invention is a method of forming a floating gate for synthesizing a nano-sized nanocrystals that can easily control the density and size using a micelle without a high temperature heat treatment process, so that it can be used as a floating gate of a nonvolatile memory device, non-using A volatile memory device and a manufacturing method thereof.

The present invention relates to a method of forming a floating gate on a semiconductor substrate, comprising: forming a tunneling oxide film on a semiconductor substrate, and a precursor capable of synthesizing a metal salt with a nanostructure formed on the tunneling oxide film by self-assembly. Coating a gate forming solution including a micelle template into which a material is introduced, and removing the micelle template on the semiconductor substrate to arrange the metal salt on the tunneling oxide layer to form the floating gate.

Nonvolatile Memory, Floating Gate, Micell Polymer, Nano Crystal, Self Assembly

Description

Method of forming floating gate and method of fabricating non-volatile memory device using the same

1A to 1H are cross-sectional views illustrating a method of manufacturing a nonvolatile memory device in accordance with a preferred embodiment of the present invention.

2 is a view for explaining a gate forming solution applied to a preferred embodiment of the present invention.

3 is a view for explaining the synthesis of metal nanocrystals according to a preferred embodiment of the present invention.

4A to 4C are cross-sectional views illustrating a method of forming a control gate of a nonvolatile memory device according to the present invention.

5A and 5B are SEM (Scanning Electron Microscopy) photographs of metal nanocrystals formed while varying the molecular weight of a micelle polymer according to an embodiment of the present invention arranged in a tunneling oxide film.

Figure 6 is a graph for explaining the state of the metal nanocrystal before and after the hydrogen atmosphere heat treatment process according to the present invention.

FIG. 7 is a graph showing capacitance corresponding to applied voltage of a nonvolatile memory device using a metal nanocrystal as a floating gate. FIG.

FIG. 8 is a graph illustrating a change in flat voltage according to time variation of a nonvolatile memory device fabricating a metal nanocrystal using a floating gate. FIG.

Explanation of symbols on the main parts of the drawings

10; Silicon Substrate 11: Tunneling Oxide

12: gate forming solution 12a: metal nanocrystal

13: control oxide film 14: control gate

The present invention relates to a method of forming a floating gate and a method of manufacturing a nonvolatile memory device using the same, and more particularly, to form a floating gate using a nano-sized nanocrystal that can easily control the density and size, At the time of formation, it is possible to omit a high temperature heat treatment process using a micelle without a high temperature heat treatment to cause a problem such as a change in film quality, and to form an oxide film with a material having a high dielectric constant, A floating gate forming method capable of applying a higher electric field and a method of manufacturing a nonvolatile memory device using the same.

With the development of semiconductor device technology, semiconductor devices such as semiconductor memory devices or thin film transistor-liquid crystal displays (TFT-LCDs) have become increasingly integrated and miniaturized.

A semiconductor memory device, such as a dynamic random access memory (DRAM) and a static random access memory (SRAM), includes a volatile memory device in which stored data is lost when power is interrupted, and a non-volatile memory device in which data is retained even when power is temporarily stopped. It can be divided into nonvolatile memory devices.

Non-volatile memory devices have an almost indefinite accumulation capacity, and there is an increasing demand for flash memory devices capable of electrically input / output of data such as electrically erasable and programmable ROM (EEPROM).

Such a nonvolatile memory device may be classified into a floating gate type and a silicon-oxide-nitride-oxide-semiconductor (SONOS) type.

The floating gate type generally has a vertically stacked gate structure having a floating gate on a silicon substrate, and the multilayer gate structure is formed on at least one tunneling oxide or dielectric film and on the floating gate and the floating gate formed on the tunneling oxide film. It includes a control gate.

Such a floating gate type flash memory device can store / delete data by applying an appropriate voltage to a control gate and a substrate to induce / spill electrons to the floating gate, and the dielectric film retains charge charged in the floating gate. To be done.

The SONOS type includes a source electrode and a drain electrode formed on a silicon substrate, a tunneling oxide film stacked on an upper surface of the substrate, a nitride film stacked on an upper surface of the tunneling oxide film, a blocking oxide film formed on an upper surface of the nitrite film, and an upper surface of the blocking oxide film. And a tunneling oxide film, a nitride film, and a blocking oxide film are generally referred to as ONO (Oxide / Nitride / Oxide) films.

Such a SONOS type flash memory device may operate a memory device in which electrons are trapped in a charge defect in a nightlight layer formed on an upper surface of a tunneling oxide layer to store information, but a SONOS type flash memory device may capture electrons. It is difficult to control / control the number of electronic defects in the nitride film.

On the other hand, in the floating gate type flash memory device, a study to use a nano-crystal (Nanocrystal) that can easily adjust the density and size of particles as a floating gate is in progress.

In order to form such a nanocrystal on a tunneling oxide film of a silicon substrate, a high temperature heat treatment process of 850 ° C or higher is required.

However, when a high temperature heat treatment process for forming nanocrystals is performed on a silicon substrate, the film quality of each component (eg, tunneling oxide) may change according to interface reactions and defects. Problems such as unnecessary diffusion of ions due to the components of the ion implantation process and the like decreases the characteristics of the device.

Therefore, a manufacturing technology of a floating gate type flash memory device capable of preventing problems caused by a high temperature heat treatment process while taking advantage of nanocrystals by using nanocrystals with easy density and size control of floating gates for floating charges is provided. It is required.

Meanwhile, a floating gate type flash memory device capable of preventing bridges between gates while sufficiently securing an overlay margin between an active region defined in a semiconductor substrate and a floating gate has been proposed in Korean Patent Publication No. 2005-0002304.

According to the Patent Publication No. 2005-0002304, it is possible to improve the reliability of a semiconductor device by ensuring the maximum overlay margin between the floating gate and the active region of the semiconductor substrate without reducing the coupling ratio between the floating gate and the control gate. However, there is no method for solving the problems caused by the high temperature heat treatment process while using the nanocrystal as a floating gate.

In addition, a method of improving the characteristics of a memory device by providing a larger electric field at the same voltage by using an oxide film having a higher dielectric constant than that of a silicon oxide film or a silicon oxynitrite film used as an oxide film of a nonvolatile memory device should be presented. do.

Accordingly, the present invention was devised to meet the above necessity, and an object thereof is to control the floating gate of a nonvolatile memory device in density and size easily, and to fabricate a nano-sized metal using a micelle template. The present invention provides a method of forming a floating gate using nanocrystals and a method of manufacturing a nonvolatile memory device using the same.

Another object of the present invention is to provide a floating gate forming method capable of forming a floating gate using a metal nanocrystal without a high temperature heat treatment process that causes a problem such as a change in film quality, and a method of manufacturing a nonvolatile memory device using the same. There is.

Another object of the present invention is to provide a nonvolatile memory device and a method of manufacturing the same, in which an oxide film, which is a dielectric film, is formed of a material having a high dielectric constant, so that a higher electric field can be applied at the same voltage.

According to an aspect of the present invention, there is provided a method of forming a floating gate on a semiconductor substrate, the method comprising: forming a tunneling oxide film on the semiconductor substrate, and forming nanostructures on the tunneling oxide film by self-assembly. Coating a gate forming solution including a micellar template into which a precursor for synthesizing a metal salt is introduced into a structure, removing the micelle template on the semiconductor substrate, and arranging the metal salt on the tunneling oxide layer to form the floating gate Forming a step.

In the floating gate forming method, the micelle template may be removed through a plasma process or a heat treatment process.

The floating gate forming method may further include reducing the metal salt when the metal salt is oxidized through the plasma process or the heat treatment process.

The reducing of the metal salt is preferably performed through any one of a step of heat treatment in a hydrogen atmosphere or a step of applying a hydrogen plasma.

) 산화막, 이산화규소(

) 산화막 및 산화알루미늄(

) 산화막 중 어느 하나의 산화막으로 형성되는 것이 바람직하다.The tunneling oxide film is hafnium oxide (

) Oxide film, silicon dioxide (

) Oxide film and aluminum oxide (

It is preferable that the oxide film is formed of one of the oxide films.

The precursor material is cobalt (Co), iron (Fe), nickel (Ni), chromium (Cr), gold (Au), silver (Ag), copper (Cu), aluminum (Al), platinum (Pt), It is a material capable of synthesizing any one metal salt of tin (Sn), tungsten (W), ruthenium (Ru), and cadmium (Cd).

In the floating gate forming method, the metal salt is introduced into the nanostructure by introducing a micelle polymer capable of forming the micelle template having a nanostructure in a self-assembling manner into a toluene solution containing the precursor. It is a metal nanocrystal to be synthesized.

In the floating gate forming method, the density of the metal nanocrystal is controlled by adjusting the corona block molecular weight or core block molecular weight of the micelle polymer.

The floating gate may be applied to a floating gate of a nonvolatile memory or a floating electrode of a thin film transistor-liquid crystal display (TFT-LCD), and the nonvolatile memory is a flash memory.

According to another aspect of the present invention, a method of manufacturing a nonvolatile memory device includes forming a tunneling oxide film on a semiconductor substrate, and introducing a precursor material for synthesizing a metal salt into a nanostructure formed on the tunneling oxide film by self-assembly. Coating a gate forming solution including a preformed micelle template, removing the micelle template on the semiconductor substrate, and arranging the metal nanocrystals synthesized with the metal salt on the tunneling oxide film, the tunneling oxide film, and the Forming a control oxide film on the metal nanocrystal, and forming a control gate on the control oxide film.

The method of manufacturing the nonvolatile memory device may include reducing the metal nanocrystal through hydrogen atmosphere heat treatment or hydrogen plasma treatment when the metal nanocrystal is oxidized while removing the micelle template through a plasma process or a heat treatment process. It includes more.

The gate forming solution is a metal nanocrystal is formed by putting the micelle polymer forming the micelle template in a self-assembly method in a toluene solution containing a precursor material, the precursor is selectively introduced into the core block of the micelle template Obtained by synthesis.

The precursor material is cobalt (Co), iron (Fe), nickel (Ni), chromium (Cr), gold (Au), silver (Ag), copper (Cu), aluminum (Al), platinum (Pt), It is a material capable of synthesizing any one metal salt of tin (Sn), tungsten (W), ruthenium (Ru), and cadmium (Cd).

In the method of manufacturing the nonvolatile memory device, the density of the metal nanocrystal is controlled by adjusting the corona molecular weight or the core molecular weight of the micelle polymer capable of forming the micelle template by self-assembly.

A nonvolatile memory device according to another aspect of the present invention is formed by self-assembly by a semiconductor substrate, a tunneling oxide film formed on the semiconductor substrate, and a micellar template having a nanostructure on the tunneling oxide film. A plurality of metal nanocrystals, a control oxide film formed on the tunneling oxide film and the metal nanocrystal, and a control gate formed on the control oxide film.

In the nonvolatile memory device, the tunneling oxide film and the control oxide film may be formed of any one of a hafnium oxide oxide film, a silicon dioxide oxide film, and an aluminum oxide oxide film.

The metal nanocrystal is synthesized by selectively introducing a precursor capable of synthesizing a metal salt into the nanostructure of the micelle template formed by the self-assembly method, and is obtained by removing the micelle template through a plasma process or a heat treatment process.

When the metal nanocrystal is oxidized through the plasma process or the heat treatment process, the metal nanocrystal reduces the metal nanocrystal through hydrogen atmosphere heat treatment or hydrogen plasma treatment.

In the nonvolatile memory device, an area in which the metal nanocrystals are not arranged has a metal-oxide-semiconductor (MOS) structure, and an area in which the metal nanocrystals are arranged is a control gate (metal gate) -control oxide layer (Oxide)- It has a metal nanocrystal (floating gate) -tunneling oxide film-silicon substrate structure.

The metal nanocrystal is a spherical shape forming a planar circle.

According to the present invention described above, the floating gate of the nonvolatile memory device can be formed of a nano-sized metal nanocrystal, the density of the metal nanocrystal forming the floating gate can be controlled, as well as a high temperature heat treatment process Without nanoscale metal nanocrystals can be formed as floating gates.

(Example)

Hereinafter, a method of forming a floating gate, a nonvolatile memory device using the same, and a method of manufacturing the same according to the present invention will be described in detail with reference to the accompanying drawings. The same can be applied to the volatile memory device.

1A to 1H are cross-sectional views illustrating a method of manufacturing a nonvolatile memory device in accordance with a preferred embodiment of the present invention.

Referring to FIG. 1A, a tunneling oxide film 11 is formed on a silicon substrate 10, which is a semiconductor substrate. The tunneling oxide film 11 is formed on an active region on the silicon substrate 10 which is divided into a field region and an active region. At this time, the tunneling oxide film 11 is preferably formed of a hafnium oxide film, a silicon oxide film or a silicon oxynitride oxide film with a thickness of 3 to 8 nm.

For example, as illustrated in FIG. 1H, the silicon substrate 10 is provided with a first impurity region 2a and a second impurity region 2b doped with an impurity 3, that is, a dopant. A channel region is formed in the silicon substrate 10 between the first impurity region 2a and the second impurity region 23b, and a gate structure 1 is formed on the channel region.

The gate structure 1 includes a tunneling oxide film 11, a floating gate made of a metal nanocrystal, a control oxide film 13, a control gate 14, and the like.

As shown in FIG. 1B, the gate forming solution 12 is coated on the tunneling oxide film 11.

2 is a view for explaining a gate forming solution applied to a preferred embodiment of the present invention.

Referring to FIG. 2, a micelle having a nano structure is formed by putting a micelle polymer formed of a polymer into a toluene solution.

The micelles included in the gate forming solution 12 may be formed in a self-assembly manner to synthesize nano-sized metal nanocrystals 12a.

That is, the metal nanocrystal 12a used as the floating gate of the nonvolatile memory device according to the present invention may be synthesized by introducing a precursor material into the nanostructure of the micelle template 12c that is self-assembled.

Unlike conventional polymer mixtures that exhibit macromolecular separations of several microns, micelle polymers contain each block due to the constraints of covalent bonds between a pair of blocks: polystyrene (PS) corona blocks and poly (vinyl pyridine (PVP) core blocks. There is a tendency to phase-separate into each domain, thereby forming nanostructures having a size of several nanometers to several hundred nanometers by self-assembly.

The micelle polymer may be formed of, for example, a polymer of a polymer by using a methylene group, a benzene group, or the like as shown in Chemical Formula 1, and the polymer may be formed by a polymer that may form other micelles in a self-assembling manner. .

In Formula 1, n and m are integers.

The shape and size of the nanostructure formed by the self-assembly of the micelle polymer may be determined according to the molecular weight of the micelle polymer, the volume ratio of each block, and the Flory-Huggins polymer solvent interaction coefficient between the blocks.

Hereinafter, the detailed description of the present invention describes a method of controlling density by controlling the molecular weight of the micelle polymer by controlling the shape and size of the nanostructure, that is, the shape and size of the synthesized metal nanocrystal 12a. Controlling the shape and size of the metal nanocrystals 12a by adjusting the volume ratio or the Flory-Huggins polymer solvent interaction coefficient between the blocks does not depart from the technical scope of the present invention.

The nanostructure formed by the self-assembly of the micelle polymer may be formed in the form of a plate, a gyroid, a cylinder, a sphere, or a hemisphere, and the shape of the nanostructure formed by the micelle template 12c by controlling the molecular weight of the micelle polymer. And size.

Such an optimal shape of the metal nanocrystal 12a for use as a floating gate is preferably circular in planar shape, because when the planar circular shape, charge and maintenance of electric charges are easy.

In addition, in order to arrange the micelles having a nanostructure on a substrate such as the silicon substrate 10, it is preferable to arrange the micelle template 12c having a controlled nanostructure in a thin film of the micelle polymer.

That is, the PVP core block of PS-PVP (polystyrene-poly (vinyl pyridine)) micelles and the substrate may be arranged on a substrate (silicon substrate) using the strong affinity of the substrate such as the silicon substrate 10.

)를 함유시켜, 마이셀 중합체가 톨루엔 용액에서 형성하는 복수개의 블록, 즉, PS-PVP 마이셀의 PVP 코어에 염화코발트가 선택적으로 도입되도록 한다.Meanwhile, the precursor 12b capable of synthesizing the metal nanocrystal 12a in the toluene solution, for example, cobalt chloride (

) To selectively introduce cobalt chloride into the plurality of blocks that the micelle polymer forms in the toluene solution, ie, the PVP core of the PS-PVP micelle.

That is, a precursor of nanoparticles (12b), for example cobalt chloride, is selectively introduced into the PVP core block of micelles consisting of a PS corona block dissolved in a solvent and a PVP core block having no nano structure. Nano sized metal salts, ie, metal nano crystals 12a, are synthesized.

Thereafter, as shown in FIG. 1B, cobalt chloride is selectively introduced to deposit the toluene solution including the micelles in which the metal nanocrystals 12a are synthesized, that is, the gate forming solution 12 on the tunneling oxide film 11. Coating is conformal.

In this case, the gate forming solution 12 may be coated on the tunneling oxide film 11 by spin coating, dip coating, spray coating, flow coating, or screen printing. The tunneling oxide film 11 may be spin coating or dip coating. It is preferable to coat on.

As illustrated in FIG. 1C, after the gate forming solution 12 is coated on the tunneling oxide film 11, the polymer micelle template 12c is removed.

 The method of removing the micelle template 12c may be a method of removing the micelle template 12c through a plasma process (for example, an oxygen plasma process) or a heat treatment process (for example, an oxygen atmosphere heat treatment process). Any known way of removing can be used.

Oxygen plasma process flows oxygen at CVD (chemical vapor deposition) equipment to MFC (Mass Flow Controller) at 10 sccm (Standard Cubic Centimeter per Minute) and maintains the pressure and then plasma treatment at 100W for about 10 minutes. The process is to remove the polymer of the polymer in the high temperature of the oxygen atmosphere.

In the following detailed description of the present invention, a case in which the micelle template 12c is removed through an oxygen plasma process will be described. However, it can be seen that the same is the case where the micelle template 12c is removed in other ways.

The metal nanocrystal 12a is synthesized by cobalt chloride, which is a precursor 12b selectively introduced into the PVP core block of the micelle template 12c included in the gate forming solution 12, and is subjected to an oxygen plasma process. When 12c is removed, the synthesized metal nanocrystal 12a is arranged on the tunneling oxide film 11.

)로 산화된다. At this time, the metal nanocrystal 12a synthesized by cobalt chloride, which is a precursor 12b selectively introduced into the PVP core block, may be cobalt oxide (cobalt oxide) which is a metal oxide by an oxygen plasma process.

Is oxidized to).

Here, since the polymer of the micelle template 12c contained in the gate forming solution 12 and arranged on the tunneling oxide film 11 is an organic material composed of carbon atoms (C) and hydrogen atoms (H), water and It is removed in the form of carbon dioxide.

Therefore, when the oxygen plasma treatment is performed, as shown in FIG. 1D, only the metal nanocrystals 12a remain on the tunneling oxide film 11.

3 is a view for explaining the synthesis of metal nanocrystals according to a preferred embodiment of the present invention.

Referring to FIG. 3, a precursor 12c (eg, cobalt chloride) is selectively introduced into a PVP core block on the tunneling oxide film 11 to synthesize a metal nanocrystal 12a. If the micelle template 12c of the polymer is removed by an oxygen plasma process in the state in which the gate forming solution 12 is coated, it can be seen that only the metal nanocrystal 12a, which is a metal oxide, is arranged on the tunneling oxide film 11. have.

The metal nano crystals 12a may be arranged in a predetermined pattern on the tunneling oxide film 11.

)와 같은 기능기를 가지는 블록이 마이셀의 나노 구조를 형성하는 경우에는 금속염(예를 들어, 염화코발트)이 이온 교환 반응을 통하여 도입될 수 있으므로, 도입되는 금속염의 종류와 후 처리 반응을 달리하여 금속 나노 크리스탈(12a)을 합성할 수 있다. At this time, a carboxyl group (-COOH) or a sulfone group (

When a block having a functional group such as) forms a nanostructure of a micelle, a metal salt (for example, cobalt chloride) may be introduced through an ion exchange reaction, and thus the metal may be different from the type of metal salt introduced and the post-treatment reaction. Nanocrystal 12a can be synthesized.

In addition, after synthesizing the metal nanocrystal 12a, the functional group forming the block is regenerated, so that the introduction of the precursor 12b and the nanocrystal forming reaction are repeated to control the size and amount of the metal nanocrystal 12a. In addition, other types of metal salts may be introduced to synthesize metal nanocrystals 12a of different components.

Thereafter, as shown in FIG. 1E, after the metal nanocrystals 12a are arranged on the tunneling oxide film 11, the metal nanocrystals 12a are oxidized through an oxygen plasma process or an oxygen atmosphere heat treatment process. The metal nanocrystal 12a, which is a metal oxide, is reduced by a heat treatment process or a hydrogen plasma process.

The hydrogen atmosphere heat treatment process may be performed for about 30 minutes at a pressure of 20 mtorr of hydrogen and 300 degrees Celsius, and the oxidized metal oxide is reduced through the hydrogen atmosphere heat treatment process.

In the detailed description of the present invention, cobalt chloride was used as the metal salt as the precursor 12b to form the metal nanocrystals 12a as cobalt (Co) oxide. However, iron (Fe) and nickel ( Ni), chromium (Cr), gold (Au), silver (Ag), copper (Cu), aluminum (Al), platinum (Pt), tin (Sn), tungsten (W), ruthenium (Ru), cadmium ( The metal nanocrystal 12a can be formed using a metal salt such as Cd).

For example, when synthesizing the metal nanocrystals 12a with a metal such as cobalt or nickel, the metal nanocrystals 12a are oxidized in an oxygen plasma process or an oxygen heat treatment process to remove the micelle template 12c. In order to improve the quality, the metal nanocrystals 12a are reduced by a hydrogen atmosphere heat treatment process or a hydrogen plasma process.

That is, when the metal nanocrystal 12a is oxidized in the process of removing the micelle template 12c, the metal nanocrystal is subjected to a hydrogen atmosphere heat treatment process or a hydrogen plasma process in order to improve electrical characteristics of the oxidized metal nanocrystal 12a. (12a) is reduced because the electrical properties that the oxidized metal nanocrystals 12a can introduce / discharge electrons are weaker than the reduced metal nanocrystals 12a.

On the other hand, in the case of synthesizing the metal nanocrystal 12a with a metal such as gold or platinum, a step of reducing the metal nanocrystal 12a since it is not oxidized in an oxygen plasma process or an oxygen plasma process for removing the micelle template 12c, In other words, no hydrogen atmosphere heat treatment step or hydrogen plasma step is required.

For example, when synthesizing the metal nanocrystal 12a with a metal oxidized by an oxygen plasma process, the metal nanocrystal 12a is reduced through a hydrogen atmosphere heat treatment process, and the metal nanocrystal 12a is a non-oxidized metal. ) Is synthesized without performing a hydrogen atmosphere heat treatment process, that is, a process of depositing the control oxide film 13.

Next, as shown in FIG. 1F, the control oxide film 13 is deposited after the metal nanocrystal 12a on the tunneling oxide film 11 is reduced.

The oxide film of the nonvolatile memory device according to the present invention, that is, the tunneling oxide film 11 and the control oxide film 13 may be deposited with a hafnium oxide oxide film, a silicon dioxide oxide film, or an aluminum oxide oxide film, wherein the hafnium oxide film has a dielectric constant of Since it is larger than the silicon oxide film or silicon oxynitride film generally used, it is possible to form a larger electric field at the same voltage.

The control gate layer 14 is deposited on the control oxide film 13 to form a control gate.

The control oxide film 13 processes the same function as the dielectric film in the conventional metal-oxide-semiconductor (MOS) structure, and the region B in which the metal nanocrystal 12a is not arranged on the tunneling oxide film 11 is controlled. It may be substantially connected to the oxide film 13.

The region B in which the metal nanocrystals 12a are not arranged on the tunneling oxide film 11 has a conventional MOS structure, and the region A in which the metal nanocrystals 12a are arranged is a metal gate-oxide (control oxide film). (13))-metal nanocrystal 12a-Oxide (tunneling oxide film 11) -Semiconductor structure.

Therefore, an appropriate voltage is applied between the control gate 14 and the substrate in the region A in which the metal nanocrystals 12a are arranged, so that electrons flow into and out of the metal nanocrystals 12a to store data / program. The control oxide layer 13 and the tunneling oxide layer 11 allow the electrons charged in the metal nanocrystal 12a formed as the floating gate to be retained.

In addition, as the region A on which the metal nanocrystals 12a are arranged on the tunneling oxide film 11 is wider, the characteristics of the nonvolatile memory device, that is, the flash memory device may be improved, so that the metal nanocrystals 12a are tunneled. It is preferable to make the density arranged on the oxide film 11 as large as possible.

이상으로 설정할 수 있다.Since the density of the metal nanocrystals 12a arranged on the tunneling oxide film 11 is closely related to the size and shape of the metal nanocrystals 12a, the density of the metal nanocrystals 12a synthesized by controlling the molecular weight of the micelle polymer is controlled. By adjusting the size and shape, it is possible to control the array density of the metal nanocrystal 12a to be the maximum value. At this time, the density of the metal nanocrystal 12a is

The above can be set.

That is, the size control of the metal nanocrystal 12a may be controlled by adjusting the molecular weight of the PVP core block or by controlling the amount of the precursor 12b introduced into the PVP core block, and the interval between the metal nanocrystals 12a. Since the silver can be controlled by adjusting the molecular weight of the PS corona block, the density of the metal nanocrystals (12a) can be controlled by controlling the molecular weight of the PS corona block and PVP core block of the micelle polymer.

Subsequently, as shown in FIG. 1G, the control gate 14 is formed on the control oxide film 13.

4A through 4C are cross-sectional process diagrams for illustrating a method of forming a control gate of a nonvolatile memory according to the present invention.

Referring to FIG. 4A, a polysilicon layer 14a used as a conductive film after the tunnel oxide film 11, the metal nanocrystal 12a, and the control oxide film 13 is formed on the silicon substrate 10, which is a semiconductor substrate. , The metal material layer 14b and the hard mask layer 15 are sequentially formed.

The metal material layer 14b is preferably formed of WSix, W, CoSix, TiSix, or the like.

4B, the photoresist pattern 16 is etched after the photoresist pattern 16 having the word line region closed is formed on the hard mask layer 15 by masking the control gate. The hard mask layer 15, the metal material layer 14b, and the polysilicon layer 14a are sequentially etched by a dry etching process used as a mask, and the polysilicon layer 14a 'and the metal material layer 14b' are laminated. Form a control gate.

Subsequently, referring to FIG. 4C, the photoresist pattern (not shown) is removed and the control oxide layer 13 is removed by a self-aligned etching process using the hard mask layer 15 ′ of the cell region as an etch barrier. The exposed portion and the exposed portion of the patterned tunnel conversion film 11 are etched to form the control gate 14.

In this case, the metal nanocrystal 12a of the unpatterned exposed portion of the tunnel oxide film 11 may be removed by an etching process after an etching process or left on the tunnel oxide film 11. At this time, the metal nanocrystal 12a remaining on the tunnel oxide film 11 does not affect the memory characteristics of the nonvolatile memory because the tunnel oxide film 11, which is a dielectric film, is etched.

It can be seen that the control gate may be formed using other known gate forming methods other than the control gate forming method as described above.

5A and 5B are SEM (Scanning Electron Microscopy) photographs of metal nanocrystals formed while varying the molecular weight of a micelle polymer according to an embodiment of the present invention arranged in a tunneling oxide film.

=47.6kg/mol,

=20.9kg/mol(Polydispersity index-=1.14)으로 형성하여, 금속 나노 크리스탈(12a)을 터널링 산화막(11) 상에 배열하면, 금속 나노 크리스탈(12a)의 밀도가 6.99×

로 측정되었다.As shown in FIG. 5A, the micelle polymer was converted to a number average molecular weight.

= 47.6 kg / mol,

= 20.9 kg / mol (Polydispersity index- = 1.14), and the metal nanocrystals 12a are arranged on the tunneling oxide film 11, the density of the metal nanocrystals 12a is 6.99 ×.

Was measured.

=31.9kg/mol,

=13.2kg/mol(Polydispersity index-=1.14)으로 형성하여, 금속 나노 크리스탈(12a)을 터널링 산화막(11) 상에 배열하면, 금속 나노 크리스탈(12a)의 밀도가 1.69×

로 측정되었다.On the other hand, as shown in Figure 5b, the micelle polymer is a number average molecular weight

= 31.9 kg / mol,

= 13.2 kg / mol (Polydispersity index- = 1.14), and the metal nanocrystals 12a are arranged on the tunneling oxide film 11, the density of the metal nanocrystals 12a is 1.69 ×.

Was measured.

As described above with reference to FIGS. 5A and 5B, when the molecular weight of the micelle polymer is adjusted, the size and shape of the metal nanocrystal 12a are controlled, so that the metal nanocrystal 12a is arranged on the tunneling oxide film 11. It can be seen that the density of is also controlled.

That is, the size control of the metal nanocrystal 12a controls the nanostructure size of the micelle template 12c by adjusting the molecular weight of the PVP core block or by controlling the amount of the precursor 12b introduced into the PVP core block. can do.

In addition, the interval between the metal nanocrystals 12a can be controlled by adjusting the molecular weight of the PS corona block, the density of the metal nanocrystals 12a is controlled by controlling the molecular weight of the PS corona block and PVP core block of the micelle polymer can do.

이상으로 설정할 수 있다.Therefore, by adjusting the molecular weight of the micelle polymer, the density of the metal nanocrystal 12a is

The above can be set.

6 is a graph illustrating the state of the metal nanocrystal before and after the hydrogen atmosphere heat treatment process according to the present invention.

) 20mtorr의 압력 및 섭씨 300도에서 대략 30분간 진행되는 수소 분위기 열처리 공정 전/후를 기준으로 XPS(X-ray Photoelectron Spectroscopy) 방식으로 측정한 그래프로, 수소 분위기 열처리 공정 이전에 금속 나노 크리스탈(12a)(코발트 산화물인 코발트 옥사이드)은 2p_3/2 peak가 781eV(전자 볼트)에서 나타나며, 이는 금속 나노 크리스탈(12a)이 산화물 상태인 것을 명시한다.6 is hydrogen (

X-ray Photoelectron Spectroscopy (XPS) method, measured before and after the hydrogen atmosphere heat treatment process for 30 minutes at a pressure of 20 mtorr and 300 degrees Celsius, shows the results of the metal nanocrystal (12a). (Cobalt oxide, cobalt oxide) has a 2p _3/2 peak at 781 eV (electron volts), indicating that the metal nanocrystal 12a is in an oxide state.

Meanwhile, the metal nanocrystal after the hydrogen atmosphere heat treatment process has a 2p _3/2 peak at 778 eV (electron volts), indicating that the metal nanocrystal 12a is reduced.

Therefore, it can be seen that the metal nanocrystal 12a in the oxide state is reduced through the hydrogen atmosphere heat treatment process, and thus, it can be used to inflow / outflow of electrons into the metal nanocrystal 12a. By reducing the oxidized metal nanocrystal 12a through, it is possible to improve the electrical properties of inflow / outflow of electrons.

In addition, it can be expected that the electrical properties of the reduced metal nanocrystal 12a is improved through a hydrogen plasma process for reducing the oxidized metal nanocrystal 12a.

FIG. 7 is a graph showing capacitance corresponding to applied voltage of a nonvolatile memory device using a metal nanocrystal as a floating gate.

FIG. 7 illustrates the reduction of the metal nanocrystal 12a through a hydrogen atmosphere heat treatment process followed by the deposition of the control oxide layer 13 and the control gate 14. It can be seen that the flat potential measured by erasing during the erasing and the flat potential measured by storing the program at 20V for 30ms at about 1.49V.

Therefore, when the metal nanocrystal 12a is used as a floating gate, it can be seen that data storage / programming and erasing can be distinguished, and the nonvolatile memory device in which the metal nanocrystal 12a is manufactured as a floating gate. It can be seen that is possible to operate.

FIG. 8 is a graph illustrating a change in flat voltage according to time variation of a nonvolatile memory device fabricating a metal nanocrystal using a floating gate.

As shown in FIG. 8, after storing and programming data in a nonvolatile memory device fabricated using the metal nanocrystal 12a as a floating gate, capacitance is measured for a predetermined time. Looking at the result of calculating the flat-band voltage, it can be seen that the flat-band voltage changed about 2 hours after the data was first stored, but the constant value was maintained thereafter. have.

Therefore, when data is programmed in a nonvolatile memory device fabricated using the metal nanocrystal 12a as a floating gate, the data is not deleted over time, thereby maintaining the nonvolatile characteristics of the memory device. .

As described above, the floating electrode of the thin film transistor-liquid crystal display device may be formed by controlling the molecular weight of the micelle polymer to control the size and density of the metal nanocrystal 12a.

For example, when a gate electrode and a floating electrode are formed on an insulating substrate in a process of manufacturing a thin film transistor-liquid crystal display device, the metal nanoparticles are synthesized according to the precursor material 12b selectively introduced into the nanostructure of the micelle polymer. The floating electrode may be formed using the crystal 12a. In addition, the detailed description about the manufacturing process of a thin film transistor liquid crystal display device is abbreviate | omitted.

Therefore, when manufacturing the thin film transistor-liquid crystal display device, it is possible to use the metal nano crystal 12a synthesized through the self-assembling micelle polymer which can easily control the size and density.

That is, the floating electrode may be formed by synthesizing the metal nanocrystals 12a on the toluene solution through the introduction and post-treatment process of the precursor 12b while the micelle polymer is added to the toluene solution.

Therefore, when manufacturing the thin film transistor-liquid crystal display device, the metal nanocrystal 12a synthesized through the self-assembling micelle polymer capable of easily controlling the size and density can be used.

That is, the floating electrode may be formed by synthesizing the metal nanocrystal 12a on the toluene solution through the introduction and post-treatment process of the precursor 12b while the micelle polymer is added to the toluene solution.

As described above, according to the present invention, the floating gate of the nonvolatile memory device can be easily adjusted in density and size, and can be formed of nanoscale nanocrystals.

In addition, according to the present invention, by forming the nanocrystals using the micelles in which the nanocrystals are self-assembled, problems such as changes in the properties of the film due to the high temperature heat treatment process for forming the nanocrystals can be prevented.

In addition, according to the present invention, the tunneling oxide layer or the control oxide layer may be formed of a hafnium oxide layer having a high dielectric constant, thereby applying a higher electric field than a conventional nonvolatile memory device at the same voltage, thereby improving memory device characteristics.

Although the present invention has been described in detail only with respect to the described embodiments, it will be apparent to those skilled in the art that various modifications and changes are possible within the technical spirit of the present invention, and such modifications and modifications belong to the appended claims.

Claims (23)

In the method of forming a floating gate on a semiconductor substrate, Forming a tunneling oxide film on the semiconductor substrate; Each of the micelles is composed of a corona block dissolved in a solvent and a core block insoluble in a solvent, and a precursor of nanoparticles capable of synthesizing a micelle polymer and a metal salt forming a nanostructure by self-assembly is dissolved in a solvent. Preparing a floating gate forming solution in which the precursor is selectively introduced into a micelle template formed of a core block; Coating the floating gate forming solution on the tunneling oxide layer and arranging a plurality of micelle templates, each of which the precursor is introduced, in a nano size on the tunneling oxide layer using an affinity between the tunneling oxide layer and the core block; Removing the micelle template and arranging a plurality of metal nanocrystals synthesized from the metal salt on the tunneling oxide layer to form the floating gate. The method of claim 1, wherein the removal of the micelle template, And removing the plasma through a plasma process or a heat treatment process. The method of claim 2, When the metal salt is oxidized through the plasma process or heat treatment process, the method further comprising the step of reducing the metal salt. The method of claim 3, wherein the reducing of the metal salt comprises: A method of forming a floating gate, characterized in that the process is performed by any one of a step of heat treatment in a hydrogen atmosphere or a step of applying a hydrogen plasma. The method of claim 1, wherein the tunneling oxide film, Hafnium oxide (

) Oxide film, silicon dioxide (

) Oxide film and aluminum oxide (

A floating gate forming method, characterized in that formed by any one of the oxide film. The method of claim 1, wherein the precursor material, Cobalt (Co), Iron (Fe), Nickel (Ni), Chromium (Cr), Gold (Au), Silver (Ag), Copper (Cu), Aluminum (Al), Platinum (Pt), Tin (Sn), A method of forming a floating gate, characterized in that the material can synthesize a metal salt of tungsten (W), ruthenium (Ru) and cadmium (Cd). The method of claim 1, wherein the micelle is made of a block polymer. According to claim 1, And controlling the corona block molecular weight or core block molecular weight of the micelle polymer to control the density of the metal nanocrystals. The method of claim 1, wherein the floating gate, A floating gate forming method, characterized in that applied to a floating gate of a nonvolatile memory or a floating electrode of a thin film transistor-liquid crystal display (TFT-LCD). 10. The method of claim 9, wherein the nonvolatile memory, Floating gate forming method characterized in that the flash memory. In the method of manufacturing a nonvolatile memory device, Forming a tunneling oxide film on the semiconductor substrate; Each of the micelles is composed of a corona block dissolved in a solvent and a core block insoluble in a solvent, and a precursor of nanoparticles capable of synthesizing a micelle polymer and a metal salt forming a nanostructure by self-assembly is dissolved in a solvent. Preparing a floating gate forming solution in which the precursor is selectively introduced into a micelle template formed of a core block; Coating the floating gate forming solution on the tunneling oxide layer and arranging a plurality of micelle templates, each of which the precursor is introduced, in a nano size on the tunneling oxide layer using an affinity between the tunneling oxide layer and the core block; Removing the micelle template and arranging a plurality of metal nanocrystals synthesized with the metal salt on the tunneling oxide layer; Forming a control oxide film on the tunneling oxide film and the metal nanocrystal; And forming a control gate on the control oxide film. The method of claim 11, wherein When the metal nanocrystals are oxidized while removing the micelle template through a plasma process or a heat treatment process, the method further includes reducing the metal nanocrystals through hydrogen atmosphere heat treatment or hydrogen plasma treatment. . 12. The method of claim 11, wherein the micelle is made of a block polymer. The method of claim 11, wherein the precursor material, Cobalt (Co), Iron (Fe), Nickel (Ni), Chromium (Cr), Gold (Au), Silver (Ag), Copper (Cu), Aluminum (Al), Platinum (Pt), Tin (Sn), A method for manufacturing a non-volatile memory device, characterized in that the material can synthesize a metal salt of any one of tungsten (W), ruthenium (Ru) and cadmium (Cd). The method of claim 11, wherein And controlling the molecular weight of the corona block or the core block of the micelle polymer capable of forming the micelle template in a self-assembling manner to control the density of the metal nanocrystals. delete delete delete delete delete delete 8. The method of claim 7, wherein the block polymer is made of polystyrene-poly (vinyl pyridine) (PS-PVP). The method of claim 13, wherein the block polymer is made of polystyrene-poly (vinyl pyridine) (PS-PVP).

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